sphingosine-1-phosphate and Carcinoma--Non-Small-Cell-Lung

Sphingosine-1-phosphate (S1P) is involved in inflammatory signaling/s associated with the development of respiratory disorders, including cancer. However, the underlying mechanism/s are still elusive. The aim of this study was to investigate the role of S1P on circulating blood cells obtained from healthy volunteers and non-small cell lung cancer (NSCLC) patients. To pursue our goal, peripheral blood mononuclear cells (PBMCs) were isolated and stimulated with S1P. We found that the administration of S1P did not induce healthy PBMCs to release pro-inflammatory cytokines. In sharp contrast, S1P significantly increased the levels of TNF-α and IL-6 from lung cancer-derived PBMCs. This effect was S1P receptor 3 (S1PR3)-dependent. The pharmacological blockade of ceramidase and sphingosine kinases (SPHKs), key enzymes for S1P synthesis, completely reduced the release of both TNF-α and IL-6 after S1P addition on lung cancer-derived PBMCs. Interestingly, S1P-induced IL-6, but not TNF-α, release from lung cancer-derived PBMCs was mTOR- and K-Ras-dependent, while NF-κB was not involved. These data identify S1P as a bioactive lipid mediator in a chronic inflammation-driven diseases such as NSCLC. In particular, the higher presence of S1P could orchestrate the cytokine milieu in NSCLC, highlighting S1P as a pro-tumor driver.

Topics: Carcinoma, Non-Small-Cell Lung; Cytokines; Humans; Inflammation; Interleukin-6; Leukocytes, Mononuclear; Lung Neoplasms; Lysophospholipids; Pneumonia; Sphingosine; Tumor Necrosis Factor-alpha

Topics: Animals; Carcinoma, Non-Small-Cell Lung; Cell Cycle Checkpoints; Humans; Lung Neoplasms; Lysophospholipids; Phosphotransferases (Alcohol Group Acceptor); Pre-B-Cell Leukemia Transcription Factor 1; Proto-Oncogene Proteins c-akt; Sphingosine

The sphingosine-1-phosphate (S1P) transporter Spns2 regulates myocardial precursor migration in zebrafish and lymphocyte trafficking in mice. However, its function in cancer has not been investigated. We show here that ectopic Spns2 expression induced apoptosis and its knockdown enhanced cell migration in non-small cell lung cancer (NSCLC) cells. Metabolically, Spns2 expression increased the extracellular S1P level while its knockdown the intracellular. Pharmacological inhibition of S1P synthesis abolished the augmented cell migration mediated by Spns2 knockdown, indicating that intracellular S1P plays a key role in this process. Cell signaling studies indicated that Spns2 expression impaired GSK-3β and Stat3 mediated pro-survival pathways. Conversely, these pathways were activated by Spns2 knockdown, which explains the increased cell migration since they are also crucial for migration. Alterations of Spns2 were found to affect several enzymes involved in S1P metabolism, including sphingosine kinases, S1P phosphatases, and S1P lyase 1. Genetically, Spns2 mRNA level was found to be reduced in advanced lung cancer (LC) patients as quantified by using a small scale qPCR array. These data show for the first time that Spns2 plays key roles in regulating the cellular functions in NSCLC cells, and that its down-regulation is a potential risk factor for LC.

Topics: Animals; Anion Transport Proteins; Apoptosis; Biological Transport; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Movement; Cell Survival; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Intracellular Space; Lung Neoplasms; Lysophospholipids; Mice; Receptors, Lysosphingolipid; RNA, Messenger; Sphingosine

Macrophages frequently infiltrate tumors and can enhance cancer growth, yet the origins of the macrophage response are not well understood. Here we address molecular mechanisms of macrophage production in a conditional mouse model of lung adenocarcinoma. We report that overproduction of the peptide hormone Angiotensin II (AngII) in tumor-bearing mice amplifies self-renewing hematopoietic stem cells (HSCs) and macrophage progenitors. The process occurred in the spleen but not the bone marrow, and was independent of hemodynamic changes. The effects of AngII required direct hormone ligation on HSCs, depended on S1P(1) signaling, and allowed the extramedullary tissue to supply new tumor-associated macrophages throughout cancer progression. Conversely, blocking AngII production prevented cancer-induced HSC and macrophage progenitor amplification and thus restrained the macrophage response at its source. These findings indicate that AngII acts upstream of a potent macrophage amplification program and that tumors can remotely exploit the hormone's pathway to stimulate cancer-promoting immunity.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Angiotensin II; Animals; Carcinoma, Non-Small-Cell Lung; Cell Communication; Cell Movement; Cell Proliferation; Gene Expression; Hematopoietic Stem Cells; Humans; Lung Neoplasms; Lysophospholipids; Macrophages; Mice; Mice, Transgenic; Signal Transduction; Sphingosine; Spleen; Tumor Burden

Hypoxia and signaling via hypoxia-inducible factor-1 (HIF-1) is a key feature of solid tumors and is related to tumor progression as well as treatment failure. Although it is generally accepted that HIF-1 provokes tumor cell survival and induces chemoresistance under hypoxia, HIF-1-independent mechanisms operate as well. We present evidence that conditioned medium obtained from A549 cells, incubated for 24 h under hypoxia, protected naive A549 cells from etoposide-induced cell death. Lipid extracts generated from hypoxia-conditioned medium still rescued cells from apoptosis induced by etoposide. Specifically, the bioactive lipid sphingosine-1-phosphate (S1P) not only was essential for cell viability of A549 cells but also protected cells from apoptosis. We noticed an increase in sphingosine kinase 2 (SphK2) protein level and enzymatic activity under hypoxia, which correlated with the release of S1P into the medium. Knockdown of SphK2 using specific small interfering RNA relieved chemoresistance of A549 cells under hypoxia and conditioned medium obtained from SphK2 knockdown cells was only partially protective. Coincubations of conditioned medium with VPC23019, a S1P(1)/S1P(3) antagonist, reduced protection of conditioned medium, with the further notion that p42/44 mitogen-activated protein kinase transmits autocrine or paracrine survival signaling downstream of S1P(1)/S1P(3) receptors. Our data suggest that hypoxia activates SphK2 to promote the synthesis and release of S1P, which in turn binds to S1P(1)/S1P(3) receptors, thus activating p42/44 mitogen-activated protein kinase to convey autocrine or paracrine protection of A549 cells.

Topics: Apoptosis; Carcinoma, Non-Small-Cell Lung; Cell Death; Cell Hypoxia; Cell Line, Tumor; Culture Media; Drug Resistance, Neoplasm; Etoposide; Humans; Lung Neoplasms; Lysophospholipids; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Phosphotransferases (Alcohol Group Acceptor); Receptors, Lysosphingolipid; RNA, Small Interfering; Sphingosine; Transfection